RPi 2 connected to Mode-S Beast receiver with modesmixer2

[dfroula]

I have a short video on YouTube showing my Mode-S Beast receiver connected to a RPi 2 using modesmixer 2 to convert the USB serial input to TCP. The TCP output port connects to ppup1090 to feed the Planeplotter servers autonomously from the Pi. Planeplotter can also connect to the same output port from modesmixer2 simultaneously.

The system establishes two Planeplotter Ground Stations with separate sharer IDs behind the firewall. Both Planeplotter and the Pi can run simultaneously, feeding the same data to the PP servers. The difference between the sharers is that the station router is configured to route incoming MLAT requests only to the Pi. However, some clever ppup1090 programming still allows Planeplotter to initiate MLAT requests. Also, the Planeplotter ground station can provide Beamfinder fixes when running, which the Pi can not.

I also added a push button and daemon that detects a long or short button press and initiates a halt or reboot without the need to log into the Pi with SSH. Handy. I also keep the Pi power supply on a UPS to avoid microSD card corruption from unexpected power failures.


https://youtu.be/GRklEx3ElOA

Regards,

Don
WD9DMP

[Triple7]

Hi Don,

I've read your various posts on the PP Yahoo list with interest. Thanks for taking the time to work through to a solution and sharing it with us.

I watched your video as well, very helpful.

A moot point perhaps but I think the set-up is actually one GS on the RPi and one MU (master user) on the PP PC and not 2 GS's. Ground stations are configured to pass raw data from a suitable receiver to other users (MU) and master users are configured to initiate Mlats.  Subtle difference. On a single PC set-up you can of course be both a GS and MU.

Tim

[dfroula]

Hi, Tim,

Right now I have two sharer codes, "eh" from the Planeplotter PC and "XB" from the RPi. Both are currently listed as valid Ground Stations, but I have the router configured to forward MLAT requests for raw data to the Pi (only).

I could conceivably change the router to point to the Planeplotter PC. As it is receiving the identical raw data stream from the Beast via modesmixer2 as the Pi, MLATs would continue to work fine, now serviced by the PC and the other sharer code.

So, I can have multiple Ground Station sharer codes, but only one device per external IP address can be active for serving raw MLAT data at one time.

Of course even though only one device can serve MLAT requests, both devices (and sharer codes) can provide identical normal sharing data to the Planeplotter servers. This happens whenever I run Planeplotter and connect to the same modesmixer2 output TCP port that is feeding ppup1090.

Master User status (the ability to initiate MLATs) is made per external IP address. It is fine to have the Pi qualify me for MU status, even though it can't initiate MU MLAT requests, and have my Planeplotter installation initiate the actual MLATs.

It took me a week to figure all of this out, but makes sense to me now after playing with it a bit.

Best regards,

Don
WD9DMP

[Triple7]

Hi Don,

I accept all you say and I wasn't trying to provoke. But to those that are perhaps less familiar with the esoterics of PP they may have read your post of having 2 active GS's as a possibility. You have explained that that is not possible behind a single router, although due to the magic of ModeSMixer2, you can appear to have 2 GS's.

There is nothing to be gained by sending identical data to the PP servers from the same location from the same hardware (receiver).

Tim

[dfroula]

Tim, I appreciate the clarifications and corrections, thanks!

The two GSs are an artifact of the fact that I had GS status on my Planeplotter "eh" sharer first, before adding the Rpi, which then was made the GS on its "XG" server. As The router now forwards MLAT requests only to the RPi in normal operation, GS status on the "eh" share is not really necessary.

I struggled with the idea of using two active uploading sharers that used the same source stream from the Beast and the modesmixer2. As the uploads of normal share data only occur every minute and the amount of extra data is minimal, it seems OK to leave the PP upload active, as I did think of one advantage.

I have a well-operating Beamfinder setup that automatically sends fixes from Mode-S radar identifiers and timings. Those fixes (a small number, granted) will get uploaded from Planeplotter, but not the Pi. The same goes for auto-MLAT fixes made by Planeplotter. I have both uploads turned on for now. I am open to suggestions!

One disadvantage of feeding through the Pi is that outbound hypersharing to other stations likely is not supported through the Pi. Hypersharing establishes a direct link between sharers for once per second updates of shared positions. Inbound hypersharing to PP seems to work fine, though.

Best,

Don
WD9DMP